Hysteresis loss, particularly at operating temperatures such as 50° C., is often attributed to rolling resistance. As a result, rolling resistance can be decreased by decreasing hysteresis loss (i.e., tan δ) at operating temperatures.
Functional polymers have successfully been employed to reduce rolling resistance. It is believed that certain functional groups, when attached to polymer chain ends, can serve to reduce free ends and/or reduce filler agglomeration, which are believed to be sources of hysteresis loss.
While functionalized polymers can be used to reduce hysteresis loss, there is also a desire to increase dynamic storage modulus, which often correlates to vulcanizate stiffness. While vulcanizate stiffness can be increased by employing larger amounts of filler materials, the increase in dynamic storage modulus often coincides with a large increase in hysteresis loss.
There is therefore a desire to increase dynamic storage modulus while minimizing the corresponding increase in hysteresis loss. In other words, it would be advantageous to increase dynamic storage modulus without observing any (or even a proportional) increase in hysteresis loss.